With Piazza Maggiore, Bologna’s main square, as the backdrop, a short video depiction of the volume, which can be seen on www.fmronline.it, was followed on Thursday night by an hourlong spectacle that included dozens of costumed dancers, a string quartet playing from a stage suspended in midair, suckling pigs roasted over a pit, a fake snowfall and a foppishly dressed acrobat walking Spiderman-style up the facade of San Petronio, the city’s cathedral.